ARCHIVED: What is the Simple Mail Transfer Protocol (SMTP)?

This content has been archived, and is no longer maintained by Indiana University. Resources linked from this page may no longer be available or reliable.

Simple Mail Transfer Protocol (SMTP) is the de facto standard for
electronic mail transport across the Internet. When you
send an email message, SMTP packages your message in a kind of
envelope and relays it to its destination. Multiple servers are often
involved in the transport of the message, and as it passes through
them, each one time-stamps and tags it. Thus, when the message
arrives, the recipient can get an idea of where it's been, and when it
was sent. SMTP also handles error messages, sending notifications to
senders when there is difficulty delivering their mail.

When you set up an email client, such as
Thunderbird or Mac OS X Mail, you must specify
an SMTP server for your outgoing mail. This may be different from the
server you use to check incoming mail. For help setting up your email
client at Indiana University, see: